THICKNESS OF THE LOESS 253 



on this a layer of loess 150 feet thick. He obtained his section prac- 

 ticall}^ by following the bluff and road cuts from the vicinity of Pries 

 lake to Gilder mound, and he assumes that because the road cut, nowhere 

 more than 10 feet deep, shows continuous loess from the base of Long 

 hill to the mound 150 feet higher, therefore the loess is 150 feet thick. 

 However, the loess in this region everywhere tends to form a mere mantle 

 extending over the ridges whose cores consist of rock or drift, or both, 

 and the probability is that on Long hill the loess does not exceed 35 feet 

 in thickness. (See also plate 16, figure 2, and plate 17, figure 1.) An 

 exposure three-quarters of a mile north of Pries lake shows a core of drift 

 and glacial joint clay to a height of 95 feet above the road, and this is 

 capped with about 25 feet of fossiliferous loess. (See also plate 16, fig- 

 ure 2.) N"umerous exposures on botli sides of the Missouri from Sioux 

 City to Kansas City show that the reported thickness of the loess in this 

 region, especially on the west side of the river, has been greatly exag- 

 gerated. The great cuts along the new Union Pacific "cut-off" in south 

 Omaha illustrate this fact. The first cut, near the intersection of 



• 



Thirty-second and B streets, is about 56 feet deep and shows a regular 

 mantle of loess 36 feet deep. The greater cut, between Forty-second 

 and Fifty-third streets, which is about a mile in length and about 100 

 feet deep (see plate 17, figure 2), shows a similar mantle, consisting of 

 two loesses, the upper yellow loess, about 25 feet deep, and the lower, less 

 uniform, about 8 feet deep. The total thickness of the loess mantle is 

 tlierefore about 33 feet. Professor Barbour has undoubtedly greatly ex- 

 aggerated the thickness of the loess on Long hill. 



The reference of the loess to glacial times is also extremely unfortunate, 

 for the organic remains in the loess preclude the possibility of a glacial 

 climate during its deposition. Before Professor Barbour can sustain 

 such an assumption he must explain the presence of the fossils in the loess 

 and the possibility under glacial conditions of the existence of the plants 

 necessary to their maintenance; he must explain also the presence of loess 

 and its fossils in the southern states, never reached by glaciers, and in the 

 extra-glacial western territory along the Platte and Eepublican rivers in 

 Nebraska. However, the discussion of these questions would involve the 

 consideration of the relative merits of the acjueous hvpothesis, to some 

 form of which Professor Barbour evidently adheres, and the asolian ' 

 hypothesis which has distinctly passed its merely conjectural stage. 



Summary ■ 



The foregoing facts lead to the following conclusions : 

 1. Gilder moimd is an ordinary mound, of interest because it contains 

 two layers of human remains, but it is not unlike other known mounds. 



